Re: [PATCH 0/2 v8] oom: capture unreclaimable slab info in oom message

["Yang Shi" <yang.s@alibaba-inc.com>]

On 10/2/17 4:20 AM, Michal Hocko wrote:
> On Thu 28-09-17 13:36:57, Tetsuo Handa wrote:
>> On 2017/09/28 6:46, Yang Shi wrote:
>>> Changelog v7 a??> v8:
>>> * Adopted Michala??s suggestion to dump unreclaim slab info when unreclaimable slabs amount > total user memory. Not only in oom panic path.
>>
>> Holding slab_mutex inside dump_unreclaimable_slab() was refrained since V2
>> because there are
>>
>> 	mutex_lock(&slab_mutex);
>> 	kmalloc(GFP_KERNEL);
>> 	mutex_unlock(&slab_mutex);
>>
>> users. If we call dump_unreclaimable_slab() for non OOM panic path, aren't we
>> introducing a risk of crash (i.e. kernel panic) for regular OOM path?
> 
> yes we are
>   
>> We can try mutex_trylock() from dump_unreclaimable_slab() at best.
>> But it is still remaining unsafe, isn't it?
> 
> using the trylock sounds like a reasonable compromise.

OK, it sounds we reach agreement on trylock. Will solve those comments 
in v9.

Thanks,
Yang

> 

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